Method and device for producing containers from thermoplastic material

Abstract

The invention relates to a method for producing containers (14) from preforms (12) made of thermoplastic material by means of a blow molding machine (10) comprising at least one temperature control device (26) and one forming device having at least two forming stations (16), wherein the preforms (12) are temperature controlled by means of the temperature control device (26) on the basis of specifiable first control parameters, and wherein one temperature-controlled preform (12) is formed by means of one of the forming stations (16), respectively, on the basis of specifiable second control parameters into a container (14), wherein at least one of the second control parameters is individually specified for each of the forming stations (16). The invention furthermore relates to a blow molding machine (10), designed for executing the method according to the invention, for producing containers (14) from preforms (12) made of thermoplastic material.

The invention claimed is: 
     
       1. A method for producing a finished container from a preform made of thermoplastic material with a blow molding machine that includes at least one temperature control device and a forming device having at least two forming stations, the method comprising:
 heating the preform to a temperature for radial and axial expansion with the temperature control device on the basis of at least one selected first control parameter to obtain a heated preform; 
 forming the heated preform into the finished container in one of the at least two forming stations on the basis of a second control parameter that is individually specified for the respective one of the at least two forming stations; 
 metrologically acquiring at least one property of the finished container, and in consideration of the metrologically acquired at least one property, adjusting the second control parameter that is individually specified for the respective one of the at least two forming stations to influence containers subsequently formed in the same respective one of the at least two forming stations to meet predetermined container specifications; 
 monitoring a time behavior of individually specified second control parameter for the respective one of the at least two forming stations, and in consideration of the monitored time behavior, deriving a change in a wear state of a component of the respective one of the at least two forming stations; and 
 having the component of the respective one of the at least two forming stations serviced or replaced, prior to failure of the component, based on the derived change in the wear state of the component. 
 
     
     
       2. The method according to  claim 1 , wherein the at least one property metrologically acquired during or after the forming of the finished container is continuously acquired. 
     
     
       3. The method according to  claim 2 , wherein the at least one property is compared to a reference property, and wherein the individually specified second control parameter is automatically adjusted in a closed control loop on the basis of the comparison between the continuously acquired property and the reference property. 
     
     
       4. The method according to  claim 3 , wherein, in addition to the individually specified second control parameter at least one further second individually specified control parameter and/or the at least one first control parameter is/are automatically adjusted in the closed control loop. 
     
     
       5. The method according to  claim 1 , wherein the individually specified second control parameter comprises one or more control parameters for pre-blowing valves of the forming stations. 
     
     
       6. The method according to  claim 1 , wherein the individually specified second control parameter comprises one or more control parameters for main blowing valves of the forming stations. 
     
     
       7. The method according to  claim 1 , wherein the individually specified second control parameter comprises one or more control parameters for stretching drives of the forming stations. 
     
     
       8. The method according to  claim 1 , wherein the individually specified second control parameter comprises one or more control parameters for throttle valves of the forming stations. 
     
     
       9. The method according to  claim 1 , wherein the at least one metrologically acquired property is a wall thickness or a wall thickness distribution or a section weight of the finished container. 
     
     
       10. The method according to  claim 1 , wherein the derived change in the wear state of the component is extrapolated to estimate a future wear state of the component. 
     
     
       11. The method according to  claim 10 , further comprising scheduling maintenance or replacement of the component based on the estimate of the future wear state of the component. 
     
     
       12. The method according to  claim 1 , wherein the forming stations each comprise at least one valve, wherein before installation of the at least one valve into each respective forming station, a valve characteristic of the valve is determined to obtain an initial value to specify an individual second control parameter associated with the valve.